instability vs preservation

instability

noun
  • The quality of being unstable. 

  • A state that is not in equilibrium, or in which a small change has a large irreversible effect. 

preservation

noun
  • The act of preserving; care to preserve; act of keeping from destruction, decay or any ill. 

  • The state of being preserved, how something has survived. 

How often have the words instability and preservation occurred in a corpus of books? (source: Google Ngram Viewer )